VPS and dedicated server peeps can use this to get around the One User Per Domain Policy and share a domain among multiple ftp users. Meaning, you can assign folders under your domain to other FTP users. Note, however, that the directory you remap will only be accessible by the user you remapped it to. Not even the 'main' domain user will be able to access it.

PHP

PHP scripts won't work in sub-directories remapped to other user's home directories because of a PHP security update DreamHost admins implemented in March 2012. Trying to run a script across users just loads a blank page with "No input file specified".

Note also that PHP scripts in remapped sub-directories - within your own home directory - can only run with the server's default PHP version.

Lighttpd on DreamHost PS

When using URL remapping on DreamHost PS together with Lighttpd and you are remapping to a different user you must not enable the enhanced security feature on the new user in order for the remap to work.